Techniques disclosed herein relate to microfabrication and, in particular, relate to photolithography and patterning processes.
In material processing methodologies (such as photolithography), creating patterned layers typically involves the application of a thin layer of radiation-sensitive material, such as photoresist, to a surface of a substrate. This radiation-sensitive material is transformed into a patterned mask (relief pattern) that can be used to etch or transfer a pattern into an underlying layer on a substrate. Patterning of the radiation-sensitive material generally involves exposure by a radiation source through a photomask onto the radiation-sensitive material using, for example, a photolithography system and associated optics. This photomask-based exposure creates a latent pattern within the radiation-sensitive material which can then be developed. Particular wavelengths of light cause portions of the radiation-sensitive material exposed to this light to change its solubility by either becoming soluble or insoluble to a particular solvent or developer chemistry. Developing refers to dissolving and removing a portion of the radiation-sensitive material to yield a topographic or physical pattern, that is, a relief pattern. For example, developing can include removal of irradiated regions of the radiation-sensitive material (as in the case of positive photoresist), or non-irradiated regions (as in the case of negative resist) using a developing solvent. The relief pattern can then function as a mask layer for subsequent processing.